1. Field of the Invention
The present invention generally relates to an endoscopic implement having two electrodes and, more particularly, to such an implement wherein each electrode is connected to a terminal of a high-frequency generator and mounted at a distal end zone of an elongated insertion element, one of the electrodes being mounted laterally to the axis of the insertion element.
2. Description of Related Art
Endoscopic implements are advanced by their elongated insertion element through the stem tube of an endoscope inserted into the body and toward a body cavity. Therein the electrodes, which are powered with high frequency current, may be used for coagulation or tissue removal. Typical applications are to the bladder, prostate or also the uterus.
As regards earlier, monoipolar procedures, the implement was fitted with only one electrode and the current was set up, through the body surface, upon contact with the tissue between the electrode and a neutral electrode. Recent bipolar implements are fitted with both electrodes at the distal end zone and, accordingly, the current is set up along the short path between them instead of through the full body.
In such an implement, as disclosed in DE 38 14 967 A1, the two electrodes are configured near each other on the surface of an insulator to carry out joint contact with the tissue. This design incurs significant drawbacks because only one of the two electrodes in contact with the tissue is able to function properly.
In an implement of this species disclosed in WO 97/24993, FIG. 9, one electrode is mounted laterally to the implement axis for the purpose of tissue contacting. The other electrode is screened by an insulator from the former electrode and mounted on the opposite side, where it is in contact with the conductive liquid filling the body cavity. A current is set up between the active electrode in contact with the tissue, over short paths of the tissue, as far as the liquid, and finally the remote neutral electrode. The insulator between the two electrodes prevents direct current flow through the liquid between the electrodes, thereby averting wasting substantial energy from the power supply.
Intrinsically, however, the use of this known implement fitted with a lateral, active electrode applies only to lateral procedures. Such an implement allows treating within a cavity only surfaces which are to its sides. Wall segments of the cavity that are situated in front of the implement, therefore, are excluded on account of geometry.
An objective of the present invention is to create an endoscopic implement that has a wider applicability and that removes the deficiencies of the devices known in the art.
In accordance with the present invention, the implement is fitted with a lateral electrode, a distally-mounted electrode, and with an insulator disposed between the lateral and distal electrode to act as a current-blocker. The invention abandons the idea that only the lateral electrode implements of the species shall be the active electrode and that the other electrode shall only serve as the neutral electrode for liquid contacting. Instead, the invention provides parity between the two electrodes, and selectively either the lateral or the distal electrode shall be the active electrode making contact with the tissue while the other electrode is then freely situated in the liquid and acts as a neutral electrode for the current return. The invention assumes that an insulator shall be an effective screen between the electrodes not only when the electrodes are mounted mutually opposite said insulator, but also when they are configured laterally and distally. When the electrodes are configured laterally and distally, the insulator shall preclude short current paths between the electrodes or, in other words, it will constrain at least the otherwise shorted current between the electrodes into detours so as to reduce power losses.
In further accordance with the present invention, the insulator has a lateral surface and an end face. The electrodes are mounted to the insulator to be mutually shielded against unwanted currents. Preferably, the electrodes are mounted centrally and directly to one of the lateral surface and the end face of the insulator.
In further accordance with the present invention, the electrodes have extended topologies or configurations. In this manner they are especially well suited to the intended purposes of coagulation and surface removal of tissue by means of the so-called vaporization method.
In further accordance with the present invention, the insulator surfaces project beyond the electrodes. When applying an electrode to the tissue surface, the rim of the insulator surface enclosing the electrode will also rest on the tissue and, in this manner, current flow between the electrodes is especially effectively blocked.